Method of incinerating pre-treated industrial wastes

ABSTRACT

A method of incinerating pretreated industrial waste, according to which the wastes conveyed to the incinerator in containers is pretreated either by deep-freezing the wastes or by volatilizing the wastes under exclusion of air, or by mixing the wastes with substances of addition or with leaning substances, e.g., mud, ash, sand, wood shavings, whereupon the thus obtained wastes, either reduced in size or in volatilized condition are fed into the fire chamber of the incinerator.

United States Patent 1191 Schuster Sept, 2, 1975 [5 METHOD OFINCINERATING 3,457,881 7/1969 Test et all 110/7 PRE TREATED INDUSTRIALWASTES 3,685,467 8/ 1972 Nlomll 110/8 3,718,284 2/1973 R1chardson..241/23 [75] In nt st Schuster, Gummersbach, 3,734,036 5 1973 Abos 110/8Germany 3,736,111 5/1973 Gardner et al.. llO/8 X 1 3,771,729 11 1973 Fbl 241 23 [73] Assignee: L. & C. Steinmuller GmbH, I ta 6 I Gummersbach,Germany Primary Examiner-Kenneth W. Sprague Flledl 1 J 1974 Attorney,Agent, or Firm-Walter Becker [21] Appl. No.: 435,089

- a 57 ABSTRACT [30] Foreign Apphcatmn Pnonty Data A method ofincinerating pretreated industrial waste, Jan. 23, 1973' Germany 2303140according to which the wastes conveyed to the incim '1 erator incontainers is pretreated either by deep- [52] 1 R; 1 10/8 P; 241/l8;freezing the wastes or by volatilizing the Wastes under 2 241/23exclusion of air, 'or by mixing the wastes with sub- [51] hit. Cl. F2367/00 stances f addition or with leaning Substances g [58] Field ofSearch 110/8 R, 8 C, 8 P, 7 R; mud ash Sand, wood Shavings whereupon thethus 241/18 23 obtained wastes, either reduced in size or in volatilized0 condition are fed into the fire chamber of the inciner [56] ReferencesCited 1 UNITED STATES PATENTS Jarvis 241/23 X ator.

7 Claims, No Drawings METHOD OF .INCINERATING PRE-TREATED INDUSTRIALWASTES The present invention relates to a method of burning pretreatedindustrial wastes which are fed into an incinerator as packages ofdifferent content and unknown composition. Whereas refuse consideredover a longer period of time is a waste of a defined and uniformcomposition, industrial waste, especially waste from the chemicalindustry differs not only from plant to plant but also within the plantfrom hour to hour. The burning of house refuse is effected inincinerators generally without any problems. On the other hand, theburning of industrial waste, particularly of the chemical industry,presents the operator of such incinerators with problems that are noteasy to solve. This is due to the character and composition of this typeof waste in contrast to house refuse. Chemical waste for instance has ahigher heating power. Moreover, chemical waste is obtained in a moresolid paste-like or liquid form and has corrosive properties. Frequentlyit smells very strong and the waste is highly toxic, may have thetendency to self-ignite and, in contrast to house refuse, the chemicalwaste cannot be intermixed in a bunker and can be introduced into theincinerator chambers only by means of specially designed devices.Chemical waste contains atoms in its molecules which when beingincinerated emit air-foreign substances so that the flue gases have tobe subjected to a washing operation. This characterization of thesewastes and this distinction over house refuse is by no means complete.It is merely intended to draw attention to the fact that incineratorsfor industrial wastes, especially for chemical wastes differfundamentally and considerably from ordinary refuse incinerators inconstruction, methods of operation, number of processing stages, type ofprocess, liability to disorders, organization in the supply andchemical-physical control, and investing and operating costs.

With a certain group of waste, namely waste from laboratories,application technical departments, test 7 operations and others, thesupply of the waste is effected in containers of different sizes ofwood, steel sheet, synthetic material, etc. Heretofore, wastes of thistype were deposited in containers or barrels on socalled safe places ofdeposit. However, laws governing ecology will eventually force theincineration of such deposits or wastes.

Literature has heretofore not disclosed any methods which make possiblea complete, i.e., soot-free incineration of the wastes involved anddeposited in containers, barrels or the like, especially disagreeablewaste substances. It is for this reason that useful methods ofincinerating wastes of the above mentioned type are of particularinterest.

The tendency of reaction, especially of chemical waste, is in part veryhigh. An intermixing of these substances is, therefore, not possible forthe sake of safety. For quite some time, therefore, these wastematerials have been deposited in the above mentioned packages or barrelsof different'sizes and have been transported stances such as old oildelivered in tank cars. These defined waste liquids such as old oil canbe pumped to the burners for the combustion chamber or can be pressedthereinto by inert gases. For waste substances in packages, barrels,etc., this possibility does not exist. Therefore, other ways and meanshave to be selected.

Methods have become known according to which the containers, barrels,etc., are conveyed into a fire chamber or burning chamber by means ofspecific charge traps in a discontinuous manner.

According to one of these methods, the packages, barrels or the like areas an entirety through a trap thrown into a rotary furnace in. adiscontinuous manner after opening up the closure or after manuallyproviding some openings in thei r cover or lid.

With this type of charging the furnace, the package or barrel bursts orthe closure springs off. The liquid content shoots into the fire chamberand evaporates at a differently fast rate depending on the compositionof the waste, and this happens frequently spontaneously. The supply ofoxygen in the fire chamber does not exceed the likewise spontaneouslyoccurring combustion per time unit. The oxygen supply is particularlywith quickly reacting waste substances too small up to two digits. Theresult is a highly incomplete combustion. Soot is formed which, onceformed, will'not burn in the post burning chamber nor can it be removedby a following electrofilter or a flue gas wash.

The soot leaves the chimney in the form of a black cloud which isvisible for some seconds over a considerable area after the barrel thelike has been charged into the combustion chamber.

Due to the explosion-like evaporation and combustion of different wastesubstances, pressure shocks are caused in the incinerator which pressureshocks over longer periods of time may damage the incinerator andthereby cause danger to tlhe operating personnel.

According to another method, the procedure is similar. The liquidcontent of the barrel or the like is poured into a rotary pipe bytilting the barrel, and the barrel content is subsequently passed intothe fire chamber. Also in this instance similar occurrences have to becoped with as with the above mentioned method.

There has also become known a method of treating municipal wasteaccording to which the waste is coked at the place where it forms. Thedrawback of this known method consists primarily in that in addition tothe coking residues, also gases and vapors form which, while beingabsorbed by suitable substances and thus not affecting the ecology, makeit necessary neverthelessto feed the coking residues as well as theabsorptherein. Aside from the fact that these one-way barrels have to bebought, in particular, this method is at least for the time being themost favorable method for the transport to an incinerator. on the otherhand, this results automatically in a number of difficulties which donot occur with the burning for instsance of liquid subtion products tocentral regenerating plants which is not possible without additionaltransporting means and thereby additional costs. In addition thereto,energy is required for the coking process which energy represents a costincreasing factor. The employment of this known method for industrialwastes which is furnished in barrels with different contents and unknowncomposition is more than problematic. It'is therefore an object of thepresent invention to provide a method which will make it possible tointroduce into the combustion chamber industrial wastes delivered withdifferent contents and unknown composition to an incinerator plant,

in such a condition and within such a period that a controllable andcomplete combustion will be obtained. This problem has been solvedaccording to the present invention by a method in which the pretreatmentof the waste substances varies whereas the further course of the method,however, is the same. The first method according to the invention ischaracterized by the following method steps:

a. The pretreatment is effected by deep freezing the waste substances;

b. the deep frozen waste substances are crushed or comminuted;

the comminuted waste substances are introduced into the fire orcombustion chamber;

in the combustion chamber the course of combustion is so controlled thatthe combustion air determined in conformity with the hourly quantity ofwaste, heating value and air excess is so selected and determined thatthe waste substances introduced into the combustion chamber per timeunit, especially those waste substances reacting at the fasstest rate,are completely burned.

The second method comprises the following method steps:

a. The pretreatment is effected by evaporating the waste substancesunder exclusion of air and with direct or indirect supply ofvolatilization heat;

11. the vapors and the evaporated residues are introduced into thecombustion chamber;

c. in the combustion chamber, the course of combus tion is so controlledthat the quantity of combustion determined on the basis of the airintroduced into the combustion chamber and based on the hourly suppliedquantity of waste, the heating value and the excess air is so determinedthat the pretreated waste substances reacting at the fastest rate, arecompletely burned.

The method steps of the third method according to the invention are asfollows: r

a. The pretreatment is effected by intermixing the waste substances withadmixed substances or with leaning substances;

b. the intermixed waste substances are introduced into the combustionchamber.

c. in the combustion chamber the course of combustion is so controlledthat the quantity of combustion air introduced into the combustionchamber is based on the hourly quantity of waste substances, the heatingvalue and the excess air is so determined and selected that thepretreated waste substances introduced per time unit, especially thewaste substances reacting at the fastest rate are burned completely.

In view of the fact that in the barrels or the like wastes of unknowncomposition are contained, particular attention has to be paid toexposing the content of the barrels or the like. For the first, secondand third methods according to the present invention, the exposing ofthe contents in said barrels or the like is suggested in such a way thatall barrels have their discharging means provided with exit openings andthat the barrel contents are compressed up to a predetermined pressurewhile the solid residues are conveyed to acomminuting device.

The exposing of the barrel contents may if desired be effected in anormal atmosphere. However, it is expedient to expose the barrelcontents as well as the comminution of the barrels in an inertatmosphere. This possibility is included likewise in the subject matterof the present invention.

According to the first method (deep freezing) it is possible accordingto-a further feature of the present invention to expose the contents ofthe barrels in such a way that the solid, liquid, or paste-like contentsof the barrels are exposed in the cooling zone by splitting up thebarrels or the like for instance by cutting them open. I

According to the second method, according to which the pretreatment ofthe wastes is effected by volitalization under air exclusion underdirect or indirect supply of the volatizing heat, it is suggestedaccording to a further development of this invention prior to thevolatilization of the wastes to mix the latter with additional orleaning substances.

In order to be able with the first method to carry out a time-wisecontrolled'extension of the course of combustion over the entire bandwidth of the prevailing wastes in such a way that the air supplycorresponding to the design of the plant will always be sufficient inthe fire chamber to permit burning the wastes completely and withoutdanger, it is furthermore suggested that the granulate of the brokendown barrels is independently of the contents of said barrels intermixedand the mixture is continuously fed into the fire chamber.

In order to further improve the heat value equalization obtained bymixing the granulates, itis further suggested for this method that thefixed waste parts be introduced into the cooling zone in a comminutedcondition and in this condition are simultaneously undercooled with thealready deep frozen liquid or paste-like mixture of wastes.

A method analogous to the heat value equalization may according to thepresent invention also be realized by feeding the undercooled comminutedfixed barrel contents or if desired said barrel contents together withthe barrels directly into the burning device.

There will now be described the individual methods which differ fromeach other merely by the pretreatment of the wastes.

According to the first method, the wastes alone or together with thebarrels are first deep cooled for which purpose for instance liquidnitrogen is employed with temperatures of approximately 1 C. The wastes,if desired together with the barrels, are first introduced into acooling installation where they pass into a liquid nitrogen bath andhere are undercooled to temperatures below I00C. The wastes are thus putinto the same condition which means they become hard like glass.Subsequentlythey are conveyed to a comminuting device which may forinstance be a crusher, and are here crushed to the desired or intendedgranular size. With these granular sizes a dosed feeding of the waste tothe fire chamber can be effected. The conveying of the waste into thefire chamber may be effected for instance by an inert gas stream by airor by other conveying means. For instance, the granulate may be fed intothe fire chamber from the top while the particles drop counter to theair stream. By the density of the individual granulates and the speed ofthe air stream there will be determined the drop times which inconformity with the granular size and fire chamber temperature willsuffice to carry out the volatilization of thegranulate and the burningof the vapors down to the bottom of the fire chamber. The'granulate'which has not yet completely volatilized and burned may for instancefinish burning for instance on a grate that will also serve for burningother solid wastes- The burning and volatilization may also be effectedfor instance in a rotary pipe or in aturbulence layer furnace into whichthe deep frozen wastes are fed directly. The granulate of. the crushedbarrels may independently of the contents of the barrels be intermixedand this mixture may in a continuous manner be fed into the firechamber. In this instance the mixing chamber is likewise undercooled.

The particular advantage obtained by this pretreatement of theindustrial waste is seen in the fact that wastes which in their naturalcondition in view of the danger of explosion cannot be intermixed, cannow be intermixed whereby an equalization of the wastes with regard totheir mean heating value will be effected. Also the intermixedgranulates are introduced into the fire chamber within such a time unitthat a controlled and complete combustion, which means a soot-freecombustion, occurs.

The solid contents of the barrels and the emptied barrels which areseparated at the discharging station and have been crushed in a separatedevice may for further improving the heat value equalization be feddirectly into the above described undercooled mixing chamber and may beintermixed with the granulate therein. Only then they are introducedinto the combustion chamber or directly after the crushing orcomminution passed into the combustion chamber.

A second possible embodiment of the pretreatment of the wastes consistsin that the wastes with or without the barrels are volatilized underexclusion of air while volatilizing heat is supplied directly orindirectly. The

vapors as well as the possibly not yet volatilized residues aresubsequently in a separate way introduced into the combustion chamberwhere they burn. With this pretreatment method, it is necessaryfundamentally to distinguish between a direct and an indirect supply ofvolatilization heat. According to the second method, the barrels or alsoonly the contents of the barrels are introduced for instance into anevaporization or volatilizing chamber where the heat transfer isefiected primarily by radiation. The indirect heat supply is effected byheating the walls from the outside, for instance by hot flue gases,electrically or by other convenient methods. When employing a directheating, the heat transfer is effected by heated oxygen-free gases, ifdesired also by liquids. Inasmuch as the melting heat of the individualsubstances differs in magnitude, the heat requirement determines thetemperature in the volatilizing chamber, and the surface formed by thecontents of the barrels determines the volatilizing speed. Regardless ofwhether a fast or a slow volatilization is effected, the transfer of thevapors to the fire chamber is effected in a predetermined time in orderto be sure that the oxygen in the fire chamber will be sufficient for acomplete combustion.

If only liquids are volatilized or evaporated, it is possible to operateat relatively low temperatures of a magnitude between 200C and 500C.Paste-like waste materials require somewhat higher temperatures. Solidwaste maaterials might require temperatures in the evaporation chamberof a magnitude from 800 to 900C. Inasmuch as the content of the barrelsis not causing the individual barrels successively 'to pass known, itwill be appreciated that for instance at a temthrough different chamberswith difi'erent high temperatures. The vapors are from the individualchambers conveyed to the fire chamber for the purpose of combustion.

The direct supply of the evaporation heat, for instance by inert gasesas well as flue gases, brings about that the vapors which form areobtained in that quantity in which they are fed together with hot gasinto the combustion chamber.

The third method for pretreating the wastes consists in that the wastematerials prior to passing into the fire chamber are intermixed withadditional or leaning substances and this mixture is then in acontinuous manner conveyed to the fire chamber whereby likewise atimewise expansion of the evaporation and combustion process will berealized. As additional substances and leaning means, various substancesmay be employed for instance mud, ash, sand, wood shavings or similarmaterials. As parameters'in addition to the type of material, the mixingratio and the temperature, also for instance the pouring height, thedensity of the poured material, the movement of the waste in the firechamber, etc., are to be taken into consideration. The mixture of wasteand leaning means is height per time unit fed either directly into thecombustion chamber or is first conveyed to a combustion chamber withdirect or indirect heating from where the vapors are conveyed to thecombustion chamber. To this end, rotary pipes, rotary tables or similardevices may be used. Leaning means such as ash or sand may, if desired,be passed through a circulatory path. For purposes of intermixing wasteand leaning means, various possibilities are available. Thus the mixturemay be effected in so-called paddleworms. Another possibility consistsin a continuous supply of the waste materials onto a belt which passestherebelow and is covered with leaning means. When paste-like wastematerials are involved, they may for instance be pressed into cavitiespre-forrned in the leaning substance. The wastes may, however, also besupplied into bowls or cups and together therewith fed into thecombustion chamber. After the combustion operation, the cups or bowlsare again withdrawn from the furnace and are charged anew. Thispretreatment method of the wastes is again effected with the idea inmind that the contents of the individual barrels is unknown. In spite ofthis fact, a continuous feeding effected over a predetermined time maybe carried out.

The discharging of the barrels is effected for instance in such a waythat the barrels are first provided with discharge openings and aresubsequently compressed. In this way if the barrel contents are liquid,the same will flow out within the predetermined time. On the other handif pastes are involved the paste will, due to the pressing step bepressed out of the barrel. In this way, it is possible to combinepaste-like contents with the leaning substances. With barrels with asolid content, the press will in response to a certain pressure turnitself off automatically. The entirely or partially emptied barrels areseparated from the mixture consisting of waste materials and leaningmaterials and are conveyed to the combustion chamber or by means of acutting or shearing device are so comminuted that they can be admittedto the mixture. Also in this instance,

for operating the distribution, especially when including thecomrninution of the barrels, inert atmosphere is expedient. The contentsof the barrels which contents are adapted to flow may also be dischargedby tilting the barrels after removal of the cover or lid.

It will be appreciated that by means of the method according to theinvention it is possible in an advantageous manner to carry out thecombustion of industrial wastes which are furnished in barrels withunknown content. It is furthermore advantageous to effect the combustionalways so that it can be controlled and will be complete to as to meetthe requirements which municipalities advance in connection withincinerators with industrial wastes.

Itis furthermore to be noted that while the methods as set forth abovecan be carried out with any suitable apparatus, an incinerator plant asset forth in my copending application, Ser. No. 435,090 Schuster, filedJan. 21, 1974 on even date herewith and entitled Incinerator Plant forPretreated Industrial Wastes and based on German patent applicationsSer. Nos. P23 03 1176-13, P 23 62 691.7, P 23 62 690.6, P 23 62 691.7, P23 62 690.6, and P 23 62 689.3, may advantageously be used forpracticing the methods set forth above.

It is, of course, to be understood that the present invention is by nomeans limited to the specific examples and methods set forth above butalso comprises any modifications within the scope of the appendedclaims.

What I claim is:

l. A method of incinerating industrial wastes fed to the incinerator incontainers of different contents and of unknown composition, whichincludes in combination the steps of: pretreating the wastes to beincinerated by deep-freezing the same, comminuting said deep-frozenwastes and feeding the same into the combustion chamber of theincinerator, and determining the combustion air for the combustionchamber on the basis of the quantity of wastes fed per hour into thecombustion chamber and on equalization based on the heating power ofsaid wastes and in the air excesscoefficient and feeding the thusdetermined quantity of air into the combustion chamber of theincinerator, the quantity of combustion air being so selected that thewastes being fed into the combustion chamber of the incinerator per timeunit, especially those reacting at the fastest rate, will be burnedcompletely.

2. A method in combination according to claim 1, which includes thesteps of providing the wastes containing containers with dischargeopenings, compressing said containers to a pressure to press at least amajor portion of the wastes in said container out of the latter forfeeding to the combustion chamber of the incinerator, and crushing thesolid residues and feeding the same intermixed with said wastes into thecombustion chamber of the incinerator.

3. A method in combination according to claim 2, in which the dischargeof the wastes from the respective container therefor and the crushing ofsaid container is effected in an inert atmosphere.

4. A method in combination according to claim 1, which includes the stepof freeing the wastes from the conatiners where the deep-freezing iseffected by splitting up the containers.

5. A method in combination according to claim 1, which includes the stepof intermixing the deep-cooled granulates of the wastes in thedeep-cooling zone prior to feeding same into the combustion chamber ofthe incinerator.

6. A method in combination according to claim 1, which includes thesteps .of reducing to a desired size the solid wastes and charging thesame into the zone where the cooling is to be effected whilesimultaneously undercooling said reduced solid wastes and mixing samewith the deep-frozen wastes.

7. A method in combination according to claim 1, in

which of the non-cooled solid wastes reduced in size and the crushedcontainer parts at least the former are fed directly to the combustionchamber of the incinerator.

1. A method of incinerating industrial wastes fed to the incinerator incontainers of different contents and of unknown composition, whichincludes in combination the steps of: pretreating the wastes to beincinerated by deep-freezing the same, comminuting said deep-frozenwastes and feeding the same into the combustion chamber of theincinerator, and determining the combustion air for the combustionchamber on the basis of the quantity of wastes fed per hour into thecombustion chamber and on equalIzation based on the heating power ofsaid wastes and in the air excess-coefficient and feeding the thusdetermined quantity of air into the combustion chamber of theincinerator, the quantity of combustion air being so selected that thewastes being fed into the combustion chamber of the incinerator per timeunit, especially those reacting at the fastest rate, will be burnedcompletely.
 2. A method in combination according to claim 1, whichincludes the steps of providing the wastes containing containers withdischarge openings, compressing said containers to a pressure to pressat least a major portion of the wastes in said container out of thelatter for feeding to the combustion chamber of the incinerator, andcrushing the solid residues and feeding the same intermixed with saidwastes into the combustion chamber of the incinerator.
 3. A method incombination according to claim 2, in which the discharge of the wastesfrom the respective container therefor and the crushing of saidcontainer is effected in an inert atmosphere.
 4. A method in combinationaccording to claim 1, which includes the step of freeing the wastes fromthe conatiners where the deep-freezing is effected by splitting up thecontainers.
 5. A method in combination according to claim 1, whichincludes the step of intermixing the deep-cooled granulates of thewastes in the deep-cooling zone prior to feeding same into thecombustion chamber of the incinerator.
 6. A method in combinationaccording to claim 1, which includes the steps of reducing to a desiredsize the solid wastes and charging the same into the zone where thecooling is to be effected while simultaneously undercooling said reducedsolid wastes and mixing same with the deep-frozen wastes.
 7. A method incombination according to claim 1, in which of the non-cooled solidwastes reduced in size and the crushed container parts at least theformer are fed directly to the combustion chamber of the incinerator.